A real-life blue-blooded family exists, ironically, in the impoverished hills of Kentucky. As they have mingled with the broader population, the number of blue children has dwindled, sadly. Via Daily Mail:
Dating back to the early 1800s, an isolated family in eastern Kentucky started producing children who were blue. As a result of a coincidental meeting of recessive genes, intermarriage and inbreeding, members of the Fugate family were born with a rare condition that made them visibly discoloured. Looking at the portrait, they appear to have been either Photoshopped, but science proves that the condition is in fact real.
It began when Martin Fugate, a French orphan, settled on the banks of eastern Kentucky’s Troublesome Creek to claim a land grant in the early 19th century. He married a red-haired American named Elizabeth Smith – who had a very pale complexion – and their union formed a genetic mutation that resulted in their descendants being born with blue skin.